Question

以下是ETL生成的查询

查询-

SELECT infaHiveSysTimestamp('SS') as a0, 7991 as a1, single_use_subq30725.a1 as a2, SUBSTR(SUBSTR(single_use_subq30725.a2, 0, 5), 0, 5) as a3, CAST(1 AS SMALLINT) as a4, single_use_subq30725.a3 as a5, single_use_subq30725.a4 as a6, SUBSTR(SUBSTR(SUBSTR(single_use_subq30725.a8, (CASE WHEN 12 < (- LENGTH(single_use_subq30725.a8)) THEN 0 ELSE 12 END), 104857600), 0, 20), 0, 20) as a7, infaNativeUDFCallString('TO_CHAR', single_use_subq30725.a5) as a8, infaHiveSysTimestamp('SS') as a9, CAST(infaNativeUDFCallDate('TRUNC', single_use_subq30725.a6, 'DD') AS DATE) as a10 FROM (SELECT (CASE WHEN 1 = t1.a1 THEN t1.a0 ELSE CAST(NULL AS TIMESTAMP) END) as a0, infaNativeUDFCallDate('TRUNC', (CASE WHEN 1 = t1.a1 THEN t1.a0 ELSE CAST(NULL AS TIMESTAMP) END), 'DD') as a1 
FROM 
    (
        SELECT MAX(t1.a0) as a0, MAX(t1.a1) as a1 
        FROM (
            SELECT mstr_load_audit.last_run_ts as a0, 1 as a1 FROM mstr_etl.mstr_load_audit WHERE interface_name='m_CTM_RAWTLogData_target_tbl'
            ) t1
        )t1
    ) single_use_subq39991
JOIN (
    SELECT w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.CREATE_TS as a0, CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.txACTION_ID AS STRING) as a1, SUBSTR(SUBSTR(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.STORE_NUM AS DECIMAL(18, 0))), (CASE WHEN 0 < (- LENGTH(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.STORE_NUM AS DECIMAL(18, 0))))) THEN 0 ELSE 0 END), 10), (CASE WHEN 0 < (- LENGTH(SUBSTR(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.STORE_NUM AS DECIMAL(18, 0))), (CASE WHEN 0 < (- LENGTH(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.STORE_NUM AS DECIMAL(18, 0))))) THEN 0 ELSE 0 END), 10))) THEN 0 ELSE 0 END), 10) as a2, SUBSTR(SUBSTR(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.LANE_NUM AS DECIMAL(18, 0))), (CASE WHEN 0 < (- LENGTH(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.LANE_NUM AS DECIMAL(18, 0))))) THEN 0 ELSE 0 END), 10), (CASE WHEN 0 < (- LENGTH(SUBSTR(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.LANE_NUM AS DECIMAL(18, 0))), (CASE WHEN 0 < (- LENGTH(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.LANE_NUM AS DECIMAL(18, 0))))) THEN 0 ELSE 0 END), 10))) THEN 0 ELSE 0 END), 10) as a3, SUBSTR(SUBSTR(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.tx_NUM AS DECIMAL(18, 0))), (CASE WHEN 0 < (- LENGTH(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.tx_NUM AS DECIMAL(18, 0))))) THEN 0 ELSE 0 END), 20), (CASE WHEN 0 < (- LENGTH(SUBSTR(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.tx_NUM AS DECIMAL(18, 0))), (CASE WHEN 0 < (- LENGTH(infaNativeUDFCallString('TO_CHAR', CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.tx_NUM AS DECIMAL(18, 0))))) THEN 0 ELSE 0 END), 20))) THEN 0 ELSE 0 END), 20) as a4, CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.LOYALTY_DEV_NUM AS DECIMAL(28, 0)) as a5, CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.tx_DT AS TIMESTAMP) as a6, CAST(w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.ETL_LOAD_DT AS TIMESTAMP) as a7, w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.tx_TS as a8 
FROM 
sourcedb.W5883634877684653839_Read_lcl_tlog_raw_2_VIEW__m_CTM_RAWTLogData_target_tbl
) 
single_use_subq30725 
WHERE (single_use_subq39991.a0 < single_use_subq30725.a0) AND (single_use_subq39991.a1 <= single_use_subq30725.a7)]

由于此查询是在蜂巢下推模式下生成的，因此我们在sql环境中添加了以下设置

SET hive.vectorized.execution.enabled=true;
SET hive.vectorized.execution.reduce.enabled=true;
SET hive.cbo.enable=true;
SET hive.compute.query.using.stats=true;
set hive.exec.orc.split.strategy=BI;
set hive.merge.tezfiles=true;

但是我们没有看到任何明显的收获。我们确实可以选择以传统的批处理方式移动此作业-通过shell脚本运行此作业。是否可以通过减少执行时间来对查询进行任何更改？我确信我们可以摆脱所有类型转换并减少执行时间。还有什么可以尝试的吗？

Answer 1

此查询加入：

JOIN (
    SELECT 
 ... SKIPPED ...
) 
single_use_subq30725 
WHERE (single_use_subq39991.a0 < single_use_subq30725.a0) AND (single_use_subq39991.a1 <= single_use_subq30725.a7)]

用作CROSS JOIN，因为未指定ON条件。进行交叉联接后，将使用此WHERE (single_use_subq39991.a0 < single_use_subq30725.a0) AND (single_use_subq39991.a1 <= single_use_subq30725.a7)

过滤数据集

实际上，它不会将行相乘，并且应作为MAP-JOIN使用，因为第一个子查询最多返回一行：

SELECT MAX(t1.a0) as a0, MAX(t1.a1) as a1

添加此设置以启用map-join：set hive.auto.convert.join=true; 检查map-join是否在EXPLAIN输出中。

但是最大的问题不是这个CROSS（MAP？）是否加入本身。在第二个查询中读取表时，它可防止谓词下推在连接之前起作用。

我建议完全删除联接并计算一次第一次查询，并在a0子句中提供a1和where作为参数。这样，您将消除不必要的连接，并且谓词下推可能直接起作用。

例如PPD可以应用于此列：w5883634877684653839_read_lcl_tlog_raw_2_view__m_ctm_rawtlogdata_target_tbl.CREATE_TS as a0

检查PPD和其他性能设置：https://stackoverflow.com/a/48296562/2700344

尽管添加了会话设置，查询仍需要花费时间

1 个答案: